Rubber derivatives



catalyst to prod e sheeted out on a rubber mill.

Patented Oct. 16, 1951 omen STATES PATENT OFFICE 2,511,345 RUBBER DERIVATIVES James D. D Ianni, Akron, Ohio, assignor to Wing- '"fo'ot fiorpdratiori, Akron,"h i o, a corporation Delawa llo Dr wi This invention relates to rubber derivatives, ,to methods for their preparationfandto' the use thereof. M r pamcmafly, itfelates to materials preparedbyreacting rubber with aurea in ,the presence of a condensation catalyst."

One object of Itlieihiiefntion 'is to produce rubmaterials withtheproduction of laminated prod- 7 ucts having outstanding physical characteristics. Other ,ob-ject'sand advantages will appear 'as the description proceeds.

According to theinvention, a mixture of rubber and a urea 's ted with a condensation e used f m d n' ..,.a e ap other p r ose and are particularly useful asjadh'esives. The practice of the inve tion is illustrated loy the following' examples and'description.

were 1 Five hundred grams of dead milled rubber and 100 grams of urea were thoroughly mixedin a small dough mixer andthenzfamhof a 4Q% solution of boron fiuorideiiifether was added dropwise over a period of, 2 3 minutes. The'mixture was then heated to 6G-?0'C.jior Z hours with continued mi,xing,' the inass "becoming homogeneous and quite plastic. The product, which weighed 614 grams, was washed with water on a washing mill and dried. Six grams of phenylbeta-naphthylamine were then milled into the product for the purpose of retarding oxidation. The final product weighed 606 grains and wasa sticky, brown, apparently homogeneous mass. It was still somewhat rubber-like and was easily Example 2 A mixture of500 grams of dead milled rubber and 100 grains of-thiourea was placed a small dough'mixr and mastic'ated until homogeneous, after which. ml. of a 40% solutionb'f boron fluoride in ether wasadded over 2-3 minutes, and the resultant mixture was heated and nasticatedLat BQ-TO" C. f ori 2lhours. Theprod uct, which weighed 610 grams, was quite similar to the product of Example 1. One percent of phenyl-beta-naphthylamine based on the weight 79811 de iva ve W ma Application November 19, 1%)46,

of the product was then milled into the product. While urea; and tlii'ourea are preferred ma" terials', various otheru'reas inayal'so be employed in theinventionj the broad class being typified by the jstructural i orniula in which X is selected from the g ou .QQn-sisting of oxygen, sulfurand selenium and in'wh' hjat a to e Ri s ydro en nd h i emainineiRs are selected frorii th'eg fo fi' consisting of galli y'l, y .a cyclician .ara kyl 'radica Further examplesofj ureas' which may be used are sym. dimeth'yl urea, monomj'ethyl j urea, monoethyl urea; N f ethyl-N"'-'ethyl urea, sy n. dietl yl urea, unsymf, r 'thyl"uijea, triethyl ureajallyl urea, .diallyl urea,"phenyl urea, N-phenyl-N'- tolyl urea; N-ethyl- N' phenyl urea, sym. diphej yl urea, .unsym- .diphen r t p en 11a benzyl urea sym;dibenzyl'urea, unsyrn. dibe'nlz 'yl urea, ,tribenzyl urea, phenethyl urea, N phenyl- N -methyl-N -phenyl urea, N-phenyl-N eu n N'-phenyl urea, ,N-methyleN phenyl"'urea; LN- .ethylj-N tolyl urea, cyclohexylurea, sym. d icyclohexyl urea," N-methyl-fN,N'-pentarnethyleiie urea, N,N'-.hexa in ethylene urea, QNqnethyl- N'fdeca d q phth "u ea, N-phehy w-be lw urea, N-methyli-N' dibenzyl urea, N- cyclohexyl- N -benzyl urea; N-cyclohexyl-N diethyl lea, N.-naphthyl- N-dicyclqhexy1 urea, N- benzyl N- phenetidyl urea and i corresponding thio and seleno ureas.' i

Although boron fluoride is a preierred catalyst, other condensation catalysts may also be employed .to proniote,the'.forrnation of ,the rubber derivatives. The condensation catalyst "apparently produces some condensation or cyclization ofthe rubber rnolecule's. In a dition rubber reacts with. the urea v 0 Produ e a co product involving -a.ildition,to or condens withthe added-material. rflhus in general, any condensation ,cataly st which will cause equidens ation or cyclization 9f,,th e rubber molecules maybe used. lThe' halijdes of'tlieamphot'eric metals arelapreterred class. ,Furtherexa nples are sulfuric acid, phenol sulfonic acid; j iuene sulfonicacid, various chlorsulfonic acidsfatlum- ,inum chloride, ferric chloride, chrom'ic chloride andeotherslwelllnown intheart.

The conditions of he reaction in preparing the rubber derivatives will vary I with the choice of catalyst and starting materials. For example, boron fluoride causes a relatively rapid reaction while a mixture of zinc chloride and glacial acetic acid is slower. In general, the temperature will be in the range from 15 to 125 C. The time of reaction may be as short as 15 minutes or as long as 3 or 4 hours. The urea may be used in widely varying proportions, 20-50% based on the rubber having been found to be satisfactory, quantities from 10-35% actually being retained by the rubber.

The rubber derivatives described are useful for many purposes but they are particularly advantageous in the preparation of adhesives and are eminently suitable for use in laminating rubber to cellulosic products, the latter type of lamination often giving considerable difiiculty, especially when the cellulose is in regenerated form, as in rayon or cellophane. In using the derivatives in the lamination of rubber to cellulose, it is sometimes, though not always, desirable to employ them in conjunction with an organic diisocyanate, this procedure being especially advantageous when the cellulose is in regenerated form. Various diisocyanates, either aromatic or aliphatic, may be used. Illustrative examples are para-phenylene diisocyanate, meta-phenylene diisocyanate, the diphenylene diisocyanates,methylene di(p-phenylene isocyanate), ethylene di(oxy trimethtylene isocyanate) and the diisocyanates of dipropyl ethers. Methylene di(p-phenylene isocyanates) gives outstanding results, may be prepared from readily available materials and constitutes a preferred example. If desired, the cellulose may be treated with the diisocyanate and thereafter treated with the rubber derivative and then laminated to rubber or, if desired, the diisocyanate may be added to the solution of the rubber derivative and the cellulose coated with the mixture. From the practical standpoint, the latter procedure is preferred and it has been found that particularly good results are obtained if a cement containing the rubber derivative and the diisocyanate is prepared and allowed to stand before use, for example, for about 24-48 hours. When a rayon cord was dipped into a 10% benzol solution of hexamethylene diisocyanate and dried and then dipped into a 5% benzol solution of the product of Example 1 and dried and then cured into rubber, the rubber-to-rayon adhesion was 18.6 pounds as compared with 4-5 pounds for untreated cord. Rayon cord similarly treated with a benzol solution of hexamethylene diisocyanate and a 10% benzol solution of the product of Example 2 gave an adhesion of 17.3 pounds. The use of the adhesive compositions has been particularly described in connection with the lamination of regenerated cellulose to rubber since this is an especially difficult problem which emphasizes the merit of the invention but the adhesives are also excellent for securing natural cellulose, such as cotton cord, to rubber and for securing rubber to cellulose derivatives and to glass fibers and for other purposes.

This application is a continuation-in-part of my copending application Serial No. 407,604 filed August 20, 1941, and now abandoned.

I claim:

1. As a new composition of matter, the product obtained by reacting 100 parts of rubber with 20-50 parts of urea at a temperature between about C. and 125 C. and in the presence of a condensation catalyst for rubber.

2. As a new composition of matter, the product obtained by reacting parts of rubber with 2050 parts of thiourea at a temperature between about 15 C. and C. and in the presence of a condensation catalyst for rubber.

3. As a new composition of matter, the product obtained by reacting 100 parts of rubber with 20-50 parts of urea at a temperature between about 15 C. and 125 C. and in the presence of a catalytic quantity of boron fluoride.

4. As a new composition of matter, the product obtained by reacting 100 parts of rubber with 20-50 parts of thiourea at a temperature between about 15 C. and 125 C. and in the presence of a catalytic quantity of boron fluoride.

5. As a new composition of matter, the product obtained by reacting 100 parts of rubber with 20-50 parts of urea at a temperature of about 60 to 70 C. in the presence of boron fluoride.

6. As a new composition of matter, the product obtained by reacting 100 parts of rubber with 20-50 parts of thiourea at a temperature of about 60 to 70 C. in the presence of boron fluoride. Y 7. As a new composition of matter, the product obtained by reacting, in the presence of a condensation catalyst for rubber and at a temperature between about 15 C. and 125 C., 100 parts of rubber and 20-50 parts of a compound having the structural formula) in which X is selected from the group consisting of oxygen, sulfur and selenium and at least one R is hydrogen and the remaining R's are selected from the group consisting of hydrogen, alkyl, aryl, alicyclic and aralkyl radicals.

8. A process which comprises reacting in the presence of a condensation catalyst for rubber and at a temperature between about 15 C. and 125 C., 100 parts of rubber and 20-50 parts of a compound having the structural formula R\ 2 R N-d-N R \R in which X is selected from the group consisting of oxygen, sulfur and selenium and at least one R. is hydrogen and the remaining Rs are selected from the group consisting of hydrogen, alkyl, aryl, alicyclic and aralkyl radicals.

JAMES D. D'IANNI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,503,429 Russell July 29, 1924 1,503,430 Russell July 29, 1924 1,981,722 Ditmar Nov. 20, 1934 2,018,643 Williams Oct. 22, 1935 2,018,644 Williams Oct. 22, 1935 2,227,777 Farmer et a1. Jan. 7, 1941 2,311,656 Grimth Feb. 23, 1943 FOREIGN PATENTS Number Country Date 333,290 Great Britain Aug. 11, 1930 

